Returning value from called function in a shell script

Question

I want to return the value from a function called in a shell script  Perhaps I am missing the syntax  I tried using the global variables  But that is also not working  The code is   lockdir  somedir  test         retval         if mkdir   lockdir          then      Directory did not exist  but it was created successfully             echo  gt  amp 2  successfully acquired lock   lockdir              retval  true          else             echo  gt  amp 2  cannot acquire lock  giving up on  lockdir              retval  false      fi     return retval     retval test   if     retval      true        then         echo  directory not created      else         echo  directory already created  fi

User · Answer

In case you have some parameters to pass to a function and want a value in return. Here I am passing "12345" as an argument to a function and after processing returning variable XYZ which will be assigned to VALUE

#!/bin/bash
getValue()
{
    ABC=$1
    XYZ="something"$ABC
    echo $XYZ
}


VALUE=$( getValue "12345" )
echo $VALUE

Output:

something12345

User · Answer

You are working way too hard   Your entire script should be   if mkdir   lockdir  2 gt   dev null  then    echo lock acquired else   echo could not acquire lock  gt  amp 2 fi   but even that is probably too verbose   I would code it   mkdir   lockdir     exit 1   but the resulting error message is a bit obscure

User · Answer

I think returning 0 for succ 1 for fail  glenn jackman  and olibre s clear and explanatory answer says it all  just to mention a kind of  combo  approach for cases where results are not binary and you d prefer to set a variable rather than  echoing out  a result  for instance if your function is ALSO suppose to echo something  this approach will not work   What then   below is Bourne Shell     Syntax  w  wrapReturn    arg1   method to wrap   arg2   variable to set  w    eval  1 read  2  lt  lt EOF    EOF eval  2    2     as in  yep  the example is somewhat silly  it s just an   example   getDay      d  date    d        d -gt 255    amp  amp  echo  Oh no a return value is 0-255    amp  amp  BAIL 0   this will of course never happen  it s just to clarify the nature of returns   return  d    dayzToSalary      daysLeft 0   if    1 -lt 26    then        daysLeft  expr 25 -  1    else      lastDayInMonth  date -d   date   Y m01   1 month -1 day    d       rest  expr  lastDayInMonth - 25       daysLeft  expr 25    rest    fi   echo  Mate  it s another  daysLeft days         main  w getDay DAY   call getDay  save the result in the DAY variable dayzToSalary  DAY

User · Answer

If it s just a true false test  have your function return 0 for success  and return 1 for failure  The test would then be   if function name  then   do something else   error condition fi

User · Answer

A Bash function can t return a string directly like you want it to  You can do three things    Echo a string Return an exit status  which is a number  not a string Share a variable   This is also true for some other shells   Here s how to do each of those options   1  Echo strings  lockdir  somedir  testlock        retval        if mkdir   lockdir      then   Directory did not exist  but it was created successfully          echo  gt  amp 2  successfully acquired lock   lockdir           retval  true      else          echo  gt  amp 2  cannot acquire lock  giving up on  lockdir           retval  false      fi     echo   retval     retval    testlock   if     retval      true    then      echo  directory not created  else      echo  directory already created  fi   2  Return exit status  lockdir  somedir  testlock        if mkdir   lockdir      then   Directory did not exist  but was created successfully          echo  gt  amp 2  successfully acquired lock   lockdir           retval 0     else          echo  gt  amp 2  cannot acquire lock  giving up on  lockdir           retval 1     fi     return   retval     testlock retval    if     retval     0   then      echo  directory not created  else      echo  directory already created  fi   3  Share variable  lockdir  somedir  retval -1 testlock        if mkdir   lockdir      then   Directory did not exist  but it was created successfully          echo  gt  amp 2  successfully acquired lock   lockdir           retval 0     else          echo  gt  amp 2  cannot acquire lock  giving up on  lockdir           retval 1     fi    testlock if     retval     0   then      echo  directory not created  else      echo  directory already created  fi

[shell] Returning value from called function in a shell script

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